Carbonaceous composite materials with snowball-like morphology

ABSTRACT

The present disclosure relates to a novel process for preparing isotropic carbonaceous composite particles with favorable crystallographic, morphological &amp; mechanical properties, wherein relatively fine carbonaceous primary particles are coated with a carbonaceous binder precursor material, agglomerated and finally heat-treated at temperatures between about 1850 and 3500° C. to convert the binder precursor material to non-graphitic or graphitic carbon, thereby resulting in stable highly isotropic carbonaceous composite materials wherein the primary particles of the aggregate are held together by the carbonized/graphitized binder. The present disclosure also relates to the isotropic carbonaceous composite particles obtainable by the process described herein. The disclosure further relates to uses of said isotropic carbonaceous composite material in various applications, including as active material in negative electrodes in lithium-ion batteries, and in secondary products containing said isotropic carbonaceous composite material.

FIELD OF THE DISCLOSURE

The present disclosure relates to a novel process for preparingisotropic carbonaceous composite particles with favorablecrystallographic and morphological properties, as well as to theisotropic carbonaceous composite particles obtainable by said process.The disclosure also relates to the uses of said isotropic carbonaceouscomposite material in various applications, including as active materialin negative electrodes of lithium-ion batteries, and other productscontaining said isotropic carbonaceous composite material.

BACKGROUND OF THE DISCLOSURE

Lithium-ion batteries are widely used in portable consumer devices likeportable computers, mobile phones, and video or photographic cameras. Inaddition, large-scale lithium batteries are an attractive batterytechnology for hybrid electric vehicles, plug-in electric vehicles, andfully electric vehicles that will have a growing future market share dueto their improved fuel economy and lowered CO₂ gas emission. The growingimportance of renewable energy production requires large energy storagesystems and large-scale lithium-ion batteries are considered aspotential battery systems used in smart grids to compensate peak powerconsumption in houses or to store the energy produced in off-gridphotovoltaic systems.

Graphite is used as the electrochemically active material in thenegative electrode of lithium-ion batteries. The graphite crystallinityis required to obtain high reversible specific charges (reversibleelectrochemical capacity) up to a theoretical value of 372 Ah/kg ofgraphite. The electrochemical redox process generating the energy isbased on the reversible electrochemical intercalation of lithium intothe graphite structure. The theoretical reversible capacity correspondsto a stoichiometry of LiC₆ of the stage-1 lithium-graphite intercalationcompound formed in this intercalation process. During the chargingprocess of the lithium-ion cell, lithium ions from the positiveelectrode containing materials such as LiCo_(x)Ni_(y)Mn_(z)O₂ wherex+y+z=1 and having a layered structure, the LiMn₂O₄ with spinelstructure, or LiFePO₄ of olivine-type migrate through the electrolyteand are intercalated in the graphite negative electrode. During thedischarge process, the lithium ions are deintercalated from the graphiteand inserted in the structure of the positive electrode material.

Details about the lithium-ion battery technology and carbonaceousnegative electrode materials are described in several reviews andmonographs (see for example: P. Novák, D. Goers, M. E. Spahr, “CarbonMaterials in Lithium-Ion Batteries”, in: Carbons for ElectrochemicalEnergy Storage and Conversion Systems, F. Béguin, E. Frackowiak (Eds.),Chapter 7, p. 263-328, CRC Press, Boca Raton FI, USA, 2010; Lithium-IonBatteries-Science and Technologies, M. Yoshio, R. J. Brodd, A. Kozawa(Eds.), Springer, New York, N.Y., 2009; Lithium Batteries-Science andTechnology, G.-A. Nazri, G. Pistoia (Eds.), Kluwer Academic Publishers,Norwell, Mass., USA, 2004; Carbon Anodes for Lithium-Ion Batteries, in:New Carbon Based Materials for Electrochemical Energy Storage Systems,I. Barsukov, C. S. Johnson, J. E. Doninger, W. Z. Barsukov (Eds.),Chapter 3, Springer, Dordrecht, The Netherlands, 2006).

Similarly, isotropic carbon materials are also advantageous for graphitebipolar plates in PEM fuel cells. Bipolar plates in fuel cells arenormally plagued by the low through-plane conductivity when flakyadditives are used. A material with a higher isotropy improves thethrough-plane conductivity of the bipolar plate.

Furthermore, isotropic carbon materials are beneficial in currentcollector coatings for various battery systems in order to achieve ahigh through-plane conductivity.

State of the Art in Graphite Particle Shaping and Coating

The rounding of platelet-like graphite particles can be achieved byspecial mechanical treatments, typically of natural graphite, in ballmills, hammer mills, or by an autogenous grinding process. Usually, inthese processes a large amount of fines or graphite dust is created thathas to be separated from the rounded graphite product, causing asignificant loss of graphite. In addition, the rounding of particlecontours does not significantly change the anisotropic arrangement ofthe crystallites contained in the particles and introduces strain intothe particles that can lead to swelling effects in lithium-ion batterieswhen this strain is released during cycling.

The coating of the graphite particles by an amorphous carbon layer atpresent is achieved in the industry mostly by mixing the graphiteparticles with coal tar pitch either in a mixing process in which thepitch is mixed either as dry powder, molten liquid, or dissolved in anorganic solvent. Subsequently the dry graphite/pitch mixture iscarbonized and subsequently calcined under inert gas conditions attemperatures around 1500° C. One major problem of this coating processis the impact of coal tar pitch or other pitch types on the environmentand health as some of the polyaromatic organic pitch ingredients(“PAHs”) are considered highly toxic, carcinogenic, and/or mutagenic.Therefore, coal tar pitch is considered as a substance of very highconcern in the European REACH regulation and requires a controlled usein existing manufacturing processes. New permissions for productionprocesses involving coal tar pitch are usually not granted by stateauthorities in Europe. Newly developed production processes thereforerequire alternatives to pitch-based coating processes that so far do notappear to exist. Pitch alternatives like special polymers or other solidorganic substances that result in high carbon yield during carbonizationare significantly more expensive, may not lead to the same quality ofcarbon coating, or are of environmental or health concern as well.

Graphitized mesocarbon microbeads (MCMB) stands for an artificialgraphitic coke with spherical particle shape. When heating coal tarpitch at about 450° C. solid spherical coke particles are formed in themelt. The spherical particles are extracted, oxidized at elevatedtemperatures in air, carbonized and finally graphitized, resulting inparticles with a smooth spherical surface.

Fast charge and discharge performance is of key importance forlithium-ion batteries in several applications. Specifically, automotivelithium-ion batteries used in fully electric vehicles or in plug-inelectric vehicles require high capacity graphite-based active materialsin the negative electrode. The alignment of the anisotropic graphiteplatelets along the platelet planes in the electrode and the electrodepore structure is considered to be responsible for the limitedlithium-ion diffusion in the porous graphite electrode. The limitationswith regard to lithium-ion diffusion and solid state diffusion oflithium are often seen as a reason for the non-ideal performancecharacteristics of graphite electrodes at high current rates duringcharge and discharge. The diffusion limitation of such graphiteelectrodes do not only reduce the cell power and charging speed, but mayalso cause the plating of metallic lithium at the negative electrodesurface during the charging of the cell at high current rates, which isconsidered as a major safety problem of lithium-ion batteries.

In commercial graphite negative electrode materials based on naturalgraphite, the platelet-like shape of graphite is often modified to amore spherical or rounded shape. Rounded carbon particle shape isnormally achieved by special mechanical treatments. The mechanicaltreatments abrade the edges thereby rounding the particles and as aconsequence increasing the fine fraction in the particle sizedistribution and creating create many surface defects that can lead toparasitic reactions in lithium-ion batteries. However, these mechanicaltreatments do not significantly change the anisotropic particlecharacter, i.e. resulting particles may show rounded particle contours,but do not avoid the problems described above.

Isotropic hard carbons have historically been used due to theirfavorable lithium intercalation/de-intercalation curves for applicationsin which fast charge and discharge and low temperature performance isimportant. The reversible capacity of these hard carbons is, however,lower than for graphite.

The importance of an isotropic pore shape and low tortuosity has beendemonstrated in positive electrodes, see D. E. Stephenson et al. J.Electrochem. Soc. 2011, 158 (7), A781.

Isotropic graphite particles can be made by agglomeration of smallerparticles in a random or at least near random orientation. However, aproblem with many agglomerated graphite particles is the inherentfragility of the particle morphology since these agglomerates aretypically only held together by adhesion (mainly through van der Waalsforces), which facilitates the integrity of the coating (if present) andtheir break-up into smaller particles, thereby resulting in a highersurface area. This instability is particularly relevant for materialthat undergoes mechanical treatments for example upon pressing thegraphite material into a negative electrode of a lithium-ion battery. Itis readily apparent that the breakage of assembled particles isproblematic, not the least in view of the change of the particlecharacteristics.

Thus, it would be desirable to produce carbonaceous materials that allowproducing electrodes exhibiting on the one hand desirable fast chargeand discharge characteristics, high reversible capacity, and/orexhibiting mechanical stability, allowing the particles to maintaintheir morphology and surface properties, for example during the pressingprocess for preparing the electrodes.

SUMMARY OF THE DISCLOSURE

The present inventors have developed a novel process to produce highlyisotropic carbonaceous particles that do not exhibit the problemsobserved with assembled graphite materials of the prior art, i.e. theymay be characterized by an isotropic morphology and high porosityfavorable for fast charge and discharge capability, high reversiblecapacity and excellent mechanical stability.

Thus, in a first aspect the present disclosure relates to carbonaceouscomposite particles, wherein said particles are comprised of amultiplicity of aggregated primary particles, and wherein said primaryparticles are held together by a carbonaceous binder material attachedto the surface of the primary particles. These composite particles arefurther characterized by any one or a combination of the followingparameters:

(i) a pressure stability, wherein the BET specific surface area does notincrease by more than 3.5 m²/g; and/or by not more than 80% (compared tothe BET specific surface area of the particles before pressing) afterpressing at 15 kN/cm² for 10 s;(ii) a mass loss of non-graphitic carbon according to thermogravimetricanalysis of less than 5%, or less than 2%, or less than 1%, or less than0.5%;and/or(iii) by having a crystalline surface with a surface crystallinityexpressed by an L_(a) of >4 nm, or >6 nm, or >10 nm, as determined bymeasuring the I_(D)/I_(G) band amplitude ratio via Raman spectroscopy.

Another aspect of the present disclosure relates to compositionscomprising the carbonaceous composite particles as defined herein. Thesecompositions may comprise one type of carbonaceous composite particlesor may comprise different types of the carbonaceous composite particlesas described herein.

Yet another aspect relates to a process for making such carbonaceouscomposite particles. The process as described herein comprises attachinga carbonaceous binder precursor material to the surface of carbonaceousparticles, optionally in the presence of a solvent, thereby forming acoating of the (primary) carbonaceous particles by the carbonaceousbinder precursor material. If a solvent was used in this step, thedispersion is dried to remove any solvent. During or after the coatingand/or the drying step, the process further comprises causingagglomeration of the coated primary carbonaceous particles. Afteragglomeration, the dry agglomerated particles are subjected to a hightemperature treatment between about 1850 and 3500° C. This heattreatment yields carbonaceous composite particles comprised of amultiplicity of aggregated primary particles, wherein said primaryparticles are held together by a carbonaceous binder material attachedto the surface of the primary particles. In other words, the primaryparticles are “glued” together by the carbonaceous binder precursormaterial which is converted to carbon or even graphite during the heattreatment at temperatures above 1850° C. (practically up to 3500° C.,though at some point economic considerations prevent a heating abovesuch temperatures).

Yet another aspect relates to the use of the carbonaceous compositeparticles or the compositions as described herein for preparing anegative electrode material for a lithium-ion battery. Consequently, anegative electrode of a lithium-ion battery comprising the carbonaceouscomposite particles as described herein as an active material in thenegative electrode of the battery is another aspect of the presentdisclosure, as is a lithium-ion battery comprising said carbonaceouscomposite particles.

A further aspect relates to an energy storage device, a carbon brush, apolymer composite material comprising the carbonaceous compositeparticles or the composition comprising said carbonaceous compositeparticles as described herein.

Yet a further aspect relates to an electric vehicle, hybrid electricvehicle, or plug-in hybrid electric vehicle comprising a lithium-ionbattery with favorable fast charge and discharge as well as lowtemperature performance properties, wherein said lithium-ion batterycomprises the carbonaceous composite particles or the compositioncomprising said carbonaceous composite particles as described herein asan active material in the negative electrode of the battery.

Yet another aspect relates to a sodium-ion battery comprising thecarbonaceous composite particles or the composition comprising saidcarbonaceous composite particles as described herein.

Another aspect of the present disclosure relates to a carbon-basedcoating exhibiting isotropic electric, mechanical or heat-conductingproperties, wherein said coating comprises the carbonaceous compositeparticles or the composition comprising said carbonaceous compositeparticles as described herein, as well as to the use of saidcarbon-based coating as a coating of a current collector in batteries.

A dispersion comprising the carbonaceous composite particles or thecomposition comprising said carbonaceous composite particles asdescribed herein is another aspect of the present disclosure.

Finally, the present disclosure also relates to a method for making abuilding block of a negative electrode, employing the carbonaceouscomposite particles or the composition comprising said carbonaceouscomposite particles as described herein.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1, panel a) shows a scanning electron microscope (SEM) image ofgraphitic carbon powder 4 prepared as described in Example 1. Panel b)is a magnification of a single spherical particle.

FIG. 2, panel a) shows a scanning electron microscope (SEM) image ofcarbon intermediate 5 prepared as described in Example 2. Panel b) is amagnification of a single spherical particle showing the presence ofnon-crystalline binder droplets on the surface.

FIG. 3, panel a) shows a scanning electron microscope (SEM) image of agraphitic carbon powder 6 prepared as described in Example 2. Panel b)is a magnification of a single spherical particle.

FIG. 4, panel a) shows a scanning electron microscope (SEM) image ofcarbon powder 7 prepared as described in Example 3. Panel b) is amagnification of a single spherical particle.

FIG. 5 shows scanning electron microscope (SEM) images of cross-sectionsof unpressed electrodes containing the active carbon mixture 13, atthree different magnifications.

FIG. 6 shows scanning electron microscope (SEM) images of cross-sectionsof pressed electrodes containing the active carbon mixture 13, at threedifferent magnifications.

FIG. 7 shows the Log differential intrusion against the pore size forsynthetic graphite, natural graphite and carbon powder 11 as measured bymercury porosimetry.

FIG. 8 shows the cumulative intrusion against the pore size forsynthetic graphite, natural graphite and carbon powder 11 as measured bymercury porosimetry.

FIG. 9 shows the incremental pore volume against the pressure forsynthetic graphite, natural graphite and carbon powder 11 as measured bymercury porosimetry.

DETAILED DESCRIPTION OF THE DISCLOSURE

The relevant disclosures in the prior art documents mentioned herein arehereby incorporated by reference in their entirety. All terms used inthe present application shall have the meaning usually employed by arelevant person skilled in the art, unless specifically definedotherwise in this disclosure.

A novel multistep-process has been developed by the present inventorswhich allows the generation of novel highly isotropic carbonaceous (i.e.graphitic or non-graphitic) composite particles that may exhibitexcellent mechanical and electrochemical properties. More specifically,the process is suitable to produce highly spherical particles with alarge content of electrolyte-accessible pores or channels (i.e., highelectrolyte diffusion capacity) in combination with relatively highxylene densities (such as above 2.20 g/cm³). This morphology isbeneficial for producing electrodes exhibiting favorable lithiumdiffusion and electrochemical capacities, leading to cells with highenergy, power density and charging speed.

These advantageous properties render the novel carbonaceous compositeparticles very useful as an active material of negative electrodes inlithium-ion batteries, particularly for applications where fast chargeand discharge as well as low temperature performance is required. Forexample, automotive lithium-ion batteries used in fully electricvehicles or in plug-in electric vehicles require high capacitygraphite-based active materials in the negative electrode that allow themanufacture of electrodes with electrolyte filled channels exhibitinglow tortuosity, allowing the lithium-ions to diffuse isotropicallydespite the fundamentally anisotropic structure of graphite, resulting,inter alia, in favorable charge/discharge and favorable low temperatureperformance.

The novel multi-step process allows the “bottom-up” construction ofhighly isotropic composite particles having the desired electrochemicalas well as mechanical properties, wherein the composite particles areconstructed from agglomerated finer primary particles that have beencoated with a carbonaceous binder material which upon carbonization athigher temperatures (typically between 1850 and 3500° C.) is convertedto graphitic or non-graphitic material stably connecting themultiplicity of fine particles resulting in a characteristic sphericalporous shape resembling a “snowball-like”, framboidal or “rose bud-like”morphology (see FIGS. 1 to 4 for details).

Such composite particles differ from merely agglomerated graphiteparticles in that they exhibit an increased mechanical stability due tothe connection of the primary particles through the carbonized bindermaterial acting as a “glue”, thereby stably holding together the finerparticles in a random orientation. Some embodiments of the carbonaceouscomposite materials described herein are unique in view of the random ornear-random orientation of the finer primary particles and the presenceof isotropically distributed pores within the composite particles,combined with an excellent mechanical stability, allowing the particlesto withstand any significant damage/breakdown during the electrodemanufacturing process.

The above-described morphology of the aggregated and optionally coatedsingle particles in the composite particle allows access of theelectrolyte through large pores, favoring the lithium diffusion in thesolid because the diffusion paths in the solid are reduced to the sizeof the primary particles of the aggregated particles. This is differentto typical amorphous carbon-coated spherical graphite particles where,for example in the case of a pitch coating process, the amorphous carboncoating will be present at the particle surface, thus also potentiallyblocking/closing the pores of the agglomerated carbonaceous particles.The lack of electrolyte-accessible pores will increase the path for thelithium diffusion to the dimension of the particle, thus no longerallowing the direct wetting with the liquid electrolyte.

Carbonaceous Composite Particles

Thus, a first aspect of the present disclosure relates to carbonaceouscomposite particles, wherein said composite particles are comprised of amultiplicity of aggregated primary particles, wherein said primaryparticles are held together by a carbonaceous binder material attachedto the surface of the primary particles. These composite particles arefurther characterized by any one or a combination of the followingparameters:

(i) a good pressure stability, wherein the BET specific surface area(BET SSA) does not increase by more than 3.5 m²/g, or more than 3.0m²/g, or more than 2.5 m²/g, or more than 2.0 m²/g, or more than 1.5m²/g, or more than 1.0 m²/g after pressing at 15 kN/cm² for 10 s (seeMaterials and Methods section below for the details how the pressuretest of the particles is conducted); alternatively or in additionwherein the BET specific surface area (BET SSA) after pressing at 15kN/cm² for 10 s does not increase by more than 100%, or more than 80%,or more than 60% compared to the BET specific surface area of thematerial before pressing;(ii) a mass loss of non-graphitic carbon according to thermogravimetricanalysis (TGA) of less than 5%, or less than 4%, or less than 3%, orless than 2%, or less than 1%, or less than 0.5% (see again Materialsand Methods section below for details on the TGA measurement);and/or(iii) a surface crystallinity expressed by an L_(a) of >4 nm, or >6 nm,or >10 nm, as determined by measuring the I_(D)/I_(G) band amplituderatio via Raman spectroscopy.

The term “aggregated” used in the context of the carbonaceous compositeparticles shall be understood to refer to a connection through someadditional carbon (graphitic or non-graphitic) on the surface of theprimary particles (the additional carbon is referred to as “carbonaceousbinder material” in the present disclosure). This is in contrast to amere “agglomeration”, where the finer particles are merely held togetherthrough relatively weak inter particle interactions (mainly van derWaals forces). Said additional carbon acting as the “glue” holdingtogether the primary particles is derived from a carbonaceous binderprecursor material attached to the surface of the primary particles(coating) which has subsequently been converted to non-graphitic orgraphitic carbon by a heat treatment of the agglomerated intermediateparticles.

It will be understood that the mass loss of any non-graphitic carbon(which may for the purpose of the mass loss parameter include pyrolyzedcarbon) generally depends on the thickness and structure of the carbonon the surface of the particles, which in turn depends on the processparameters as well as on the amount and carbon yield of the carbonsource employed for the coating of the primary particles. For example,at high temperature (>1850° C.), the binder precursor material isconverted almost completely into graphitic or non-graphitic carbonexhibiting very few heteroatoms or defects. Consequently, it was foundthat the mass loss of primarily pyrolyzed carbon was less than 0.5% inthe working examples below, demonstrating that only traces of pyrolyzedor amorphous carbon remain on the surface of the particles.

As can be seen from sample materials obtained according to the processof the present disclosure (cf. FIGS. 1 to 4), the carbonaceous compositeparticles may be further characterized by a “snowball-like”, or“framboidal”, or “rose bud-like” morphology, i.e. a distinctive roundshape consisting of a multiplicity of distinct smaller primary particlesstably connected through the carbon bridges, as described above.

In some embodiments, the carbonaceous composite particles may be furthercharacterized by a near-random or random orientation of the primaryparticles forming the aggregated composite particle.

Yet another feature that may be used to characterize certain embodimentsof the carbonaceous composite particles described herein is that theparticles are rather isotropic in terms of their electrical, mechanical,and/or heat-conductive properties, as compared to, for example highlyoriented pyrolytic graphite (HOPG) that exhibits anisotropic electricalconductivity by a factor of 1000. Isotropic in the present contextshould be understood to mean that the respective properties of theparticles in different directions does not differ by more than a factorof 40, or more than a factor of 20 or more than a factor of 10 (e.g. asreflected by measured [004]/[110] XRD ratios of <4 or even <3), incontrast to anisotropic unmodified natural or synthetic graphite. Forexample, the measured [004]/[110] XRD ratio (area) of the graphitematerial 8 in comparative Example 4 is 180.

The isotropy of the carbonaceous composite particles may in certainembodiments be further characterized by a ratio of the peak areas of the[004] and [110] reflections (peak area % [004]/[110]) of lower than 10,or lower than 8, lower than 6, or lower than 4, or lower than 3, orlower than 2. The small values for the [004]/[110] ratio of the peakareas reflect the isotropic distribution of the crystalline domainswithin the particle, and thus also the random orientation of the primaryparticles in the composite particles. The theoretical [004]/[110] ratiofor a fully isotropic distribution of the crystalline domains would be1.56.

In some embodiments, the carbonaceous composite particles according tothe present disclosure may be additionally characterized by any one ofthe following parameters, alone or in combination:

(i) a BET specific surface area (BET SSA) of between 0.3 and 20 m²/g, orof between 1 and 15 m²/g, or between 1 and 10 m²/g, or between 1 and 5m²/g;(ii) a crystallite size L_(c) of less than 300 nm, or less than 250 nm,or less than 200 nm;(iii) an L_(c)/L_(a) ratio of at least 1, or at least 1.5, or at least2, or at least 2.5, or at least 3; and/or(iv) a xylene density (according to DIN 51 901) of at least 2.00 g/cm³,or at least 2.10 g/cm³, or at least 2.15 g/cm³ or at least 2.20 g/cm³;(v) a spring-back of between 10 and 90%, or between 15 and 80%, orbetween 20 and 70%, or between 30 and 60%;and/or(vi) the carbonaceous binder material connecting said primary particlesbeing graphitic, or non-graphitic carbon, or both.

With regard to the latter, the carbonaceous binder material attached tothe surface of said primary particles of the carbonaceous compositeparticles according to the present disclosure is in some embodimentsgraphitic carbon, i.e., the carbonaceous binder precursor materialcoating the primary particles has been converted to graphitic carbonduring the heat treatment step at elevated temperatures above 1850° C.for a sufficient time to achieve the graphitization of the binderattaching the primary particles to their neighbors. In such embodiments,the binder present on the surface of the composite particles istypically also converted to graphite, which means that such particleshave a relatively high surface crystallinity. However, since it is notexcluded that the resulting composite particles may be additionallymodified subsequently to the heat treatment, in some embodiments, thesurface may also be coated with, for example, other materials such asamorphous carbon despite the fact that the binder is still graphiticcarbon (e.g. through a subsequent CVD coating and the like).

In other embodiments, the carbonaceous binder material attached to thesurface of said primary particles of the carbonaceous compositeparticles according to the present disclosure is non-graphitic carbon,i.e., the carbonaceous binder precursor material coating the primaryparticles has only been carbonized (not converted to graphitic carbon,or not entirely) during the heat treatment step at elevated temperaturesabove 1850° C. It is readily apparent that composite particles whereparts of the binder have been graphitized and other parts of the binderin the composite particles have only been carbonized represent anotherpossible embodiment of the present disclosure. It will be understoodthat the degree of graphitization of the binder precursor material canbe influenced by the conditions and duration of the heat treatmentapplied to generate the composite particles of the present disclosure.

A related, but independent parameter possibly characterizing thecarbonaceous composite particles is the interlayer distance c/2. Incertain embodiments, the carbonaceous composite particles arecharacterized by an interlayer distance c/2 of 0.338 nm or less, or0.337 nm or less. Such composite particles are referred to herein as“graphitic composite particles”. In other embodiments, the carbonaceouscomposite particles are characterized by an interlayer distance c/2 ofmore than 0.338 nm, more than 0.339 nm, or more than 0.340 nm. Suchcomposite particles are referred to herein as “non-graphitic compositeparticles”.

For most applications it is desirable that the average size of theparticles does not exceed 30-40 μm. Since the composite particles are bydefinition formed by a multiplicity of primary carbonaceous particles,the average length of the major axis of the primary particles asobserved by scanning electron microscopy (SEM) is in certain embodimentsbetween 1 and 15 μm, or between 1 and 10 μm, or between 1 and 7 μm, oreven between 1 and 5 μm, as for example illustrated in FIGS. 1 to 4.

The primary particles forming the carbonaceous composite particles mayin most embodiments be selected from a carbonaceous material such asnatural graphite, synthetic graphite, graphene, graphene nanoplatelets,graphene or carbon fibers, fullerenes, nanographite, hard carbon, softcarbon, petroleum- or coal-based coke, graphitized fine coke, char,carbon black, carbon nanotubes (CNT), including single-walled nanotubes(SWNT), multiwalled nanotubes (MWNT), or mixtures of any of theforegoing. The carbonaceous material forming the primary particles inthe composite particles described herein may in certain embodiments bemixed with one or more non-carbonaceous materials, such as silicon,silicon oxide, tin, tin oxide or tin dioxide, aluminum, bismuth, lithiumtitanate, or mixtures of any of the foregoing non-carbonaceousmaterials. However, given that the heat treatment step at elevatedtemperatures may lead to undesirable chemical reactions (e.g. as theformation of silicon carbide), non-carbonaceous primary particles arenot preferred.

In order to achieve a high level of isotropy of the particles, it is incertain embodiments desirable that even the primary particles in thecomposite particles exhibit a shape that is as spherical as possible.Since natural graphite typically has a flake-like morphology, it is notpossible to provide such spherical primary particles from unmodifiednatural graphite, unless they are ground to a very small size in whichcase the anisotropic morphology becomes less pronounced. Thus, modified,rounded graphite (synthetic or natural) or non-graphitic particles (suchas coke) can be used as primary particles in such embodiments. Suitableexamples include coke, carbon black, graphitized fine coke, spherical(synthetic or natural) graphite, or micronized ultrafine orsubmicron-sized synthetic or natural graphite, and the like.

It is apparent that the primary particles may not necessarily behomogeneous. Thus, in some embodiments the primary particles areselected from a single material, optionally from a single carbonaceousmaterial, as listed above. In other embodiments, the primary particlesare selected from at least 2, 3, 4, or at least 5 different carbonaceousor non-carbonaceous materials. Preferably at least one material formingthe primary particles is a carbonaceous material.

As explained above, the carbonaceous binder material connecting themultiplicity of primary particles can be graphitic, non-graphitic, orboth. This does not only depend on the heat treatment condition andduration, but also on the selection of the carbonaceous binder precursormaterial that is converted into carbon during the formation of thecomposite particles of the present disclosure.

The carbonaceous binder material is, already for reasons of economy, insome embodiments the same for all primary particles in the compositeparticle, i.e. only one type of carbonaceous binder precursor materialhas been used for the preparation of the composite particles. However,in certain embodiments, it may be advisable to use differentcarbonaceous binder precursor material, which may lead to carbonaceouscomposite particles wherein the carbonaceous binder material is notidentical/different for at least a portion of the primary particles inthe composite particle. In these embodiments, at least 2, 3, 4, 5, ormore different carbonaceous binder materials may be present in acomposite particle.

This can be achieved by using at least 2, 3, 4, 5, or more differingcarbon binder precursor materials which result in different carbonlayers after the heat treatment step. Alternatively, the samecarbonaceous binder precursor material or different carbonaceous binderprecursor materials can also lead to different carbonaceous binders whenthe multiple carbonaceous binder precursor materials are attached to thesurface of the primary particles by different coating methods, which maylikewise have an influence on the final structure of the binder insidethe composite particles.

In terms of suitable techniques for obtaining the carbonaceous bindermaterial attached to the surface of the primary particles, theseinclude, but are not limited to the following techniques generally knownin the art:

(i) mixing of primary carbonaceous particles with a carbonaceous binderprecursor material and subsequent carbonization of said carbonaceousbinder precursor material;(ii) mixing of primary carbonaceous particles with a carbonaceous binderprecursor material and subsequent graphitization of said carbonaceousbinder precursor material;(iii) melting of a carbon precursor onto the primary particles;(iv) pitch-coating,(v) pyrolysis,(vi) evaporation.

Of these, creating a dispersion—with or without solvent—with the primarycarbonaceous particles and the carbonaceous binder precursor material(e.g. by mixing the two components together, followed by drying of thedispersion if necessary), and subsequent agglomeration and heattreatment to effect conversion of the binder precursor material intocarbonized/graphitized binder holding together the primary particles inthe composite material is particularly suitable due to its simplicityand possibility to use environmentally friendly processes and materials,e.g. a coating based on non-hazardous organic precursor molecules withwater as a solvent. However, other methods to attach the precursor tothe surface of the primary particles can likewise be used, provided thecoated particles can be assembled into agglomerated intermediateparticles that undergo a heat treatment as described herein below inmore detail.

The carbonaceous composite particles according to the present disclosuremay in certain embodiments be further characterized by a particle sizedistribution (PSD) of the composite particles having

(i) a D₉₀ value ranging from 5 to 70 μm, or from 10 to 50 μm, or from 12to 30 μm; or from 12 to 25 μm and/or(ii) a D₅₀ value ranging from 2 to 30 μm, or from 5 to 25 μm, or from 10to 20 μm and/or(iii) a D₁₀ value ranging from 0.5 to 20 μm, or from 2 to 10 μm, or from3 to 8 μm.

In some preferred embodiments, the particle size distribution value D₉₀does not exceed 35 μm, or does not exceed 30 μm, or does not exceed 25μm.

As briefly noted below, in some embodiments, especially when the heattreatment was not carried out for long enough to fully graphitize thebinder on the surface of the particles, the carbonaceous compositeparticles may be further characterized by a non-graphitic (e.g.pyrolyzed or amorphous) carbon coating on the surface of the compositeparticles. This may for example be assessed by determining the amplituderatio of the amplitudes of the D and G bands in RAMAN spectroscopy(I_(D)/I_(G)).

Given that the novel process of the invention allows the use ofnon-hazardous carbon precursors for the coating of the primary particles(i.e. (coal tar) pitch coatings are not required), the carbonaceouscomposite particles according to the present disclosure can in someinstances be further characterized by having a low polycyclic aromatichydrocarbon (PAH) concentration. The PAH concentration of theseparticles in these instances is less than 200 mg/kg, less than 150mg/kg, less than 100 mg/kg, less than 30 mg/kg, less than 10 mg/kg, lessthan 5 mg/kg, less than 2 mg/kg, less than 1 mg/kg, or even less than0.5 mg/kg.

Finally, the carbonaceous composite particles may in some embodimentsfurther comprise an additive selected from the group consisting ofcarbon black, colloidal graphite, graphene, graphene nanoplatelets,graphene or carbon fibers, fullerenes, nanographite, hard carbon, softcarbon, petroleum- or coal-based coke, graphitized fine coke, char,carbon nanotubes (CNT), including single-walled nanotubes (SWNT),multiwalled nanotubes (MWNT), metals/metalloids such as silicon,aluminum, tin, silver, copper, nickel, antimony, germanium,metal/metalloid oxides such as TiO₂, lithium titanate, SiO_(x), orSnO_(x), chalcogenides, or metal alloys, optionally wherein themetals/metalloids are selected from silicon, aluminum, or tin, or alloyscomprising said metals.

The carbonaceous composite particles are in certain embodiments furthercharacterized by a Scott density (apparent or poured density) of aboveabout 0.25 g/cm³, or above about 0.30 g/cm³, or above about 0.33 g/cm³.

In some embodiments of this aspect of the present invention, thecarbonaceous composite particles may be further characterized by aporosity determined by mercury intrusion porosimetry of at least about50%, or at least about 60%, or at least about 65%, or 70%.

Finally, the carbonaceous composite particles may in certain embodimentsbe further characterized by, inter alia, a high lithium acceptance,increased power and electrochemical capacity, fast charge and dischargeperformance, and favorable low temperature performance. For example, incertain embodiments the carbonaceous composite particles describedherein may be further characterized by a charge/discharge ratecapability 2 C/0.2 C of at least 97%, or at least 98%, or at least 99%,or at least 99.5% when present as an active material in a negativeelectrode of a lithium-ion battery. The charge/discharge rate capabilityis one of the most relevant properties of cathode materials for lithiumbatteries that would be advantageous to improve, in particular whenenvisaging high power density applications such as automotiveapplications.

Another aspect of the present disclosure relates to compositionscomprising the carbonaceous composite particles as defined herein.

In some embodiments, the composition comprising the carbonaceouscomposite particles as defined herein is mixed together with one or moreother types of carbonaceous composite particles as defined herein, butdifferent from the first carbonaceous composite particles (i.e. mixturesof at least two different carbonaceous composite particles according tothe present disclosure). For example, composite particles made fromdifferent carbon precursors, such as (non-graphitizable) hard carbon,and graphitic or graphitizable starting materials, may be combined,resulting in isotropic carbon active materials that exhibit thefavorable high rate properties of hard carbon-type active materials(L_(c) of about 10 nm) and the high capacity provided by graphiticactive materials (with an L_(c)>70 nm).

Alternatively or in addition, the composition comprising thecarbonaceous composite particles or the composition comprising a mixtureof at least two types of carbonaceous composite particles as definedherein may further contain yet another type of unmodified or modifiedcarbonaceous particles. In particular, as illustrated in Example 4, ithas been found that mixing the carbonaceous composite particles asdescribed herein with a high capacity but less spherical graphiticactive material, e.g. as disclosed in WO 2016/008951, may yield anactive carbonaceous material with excellent electrochemical properties.Accordingly, in some embodiments, the present invention relates tocompositions comprising the carbonaceous composite particles asdescribed herein in a mixture with one or more high capacitysurface-modified hydrophilic graphite(s).

Process for Preparing Carbonaceous Composite Particles

One aspect of the present disclosure relates to a novel process forpreparing carbonaceous composite particles such as the carbonaceouscomposite particles described and characterized herein. With the novelprocess, it is possible to produce highly isotropic carbonaceous, e.g.graphitic, composite particles that exhibit advantageous properties interms of their electrochemical behavior and their mechanical stability.The combined favorable properties make such particles an extremelypromising active material in negative electrodes in lithium-ionbatteries, for example in the automotive sector and related areas whereit is important to employ lithium-ion batteries characterized not onlyby a high reversible capacity but also by a fast charge and dischargeperformance.

The novel process ensures that the resulting isotropic compositeparticles have isotropically distributed pores allowing high lithium-iondiffusion rates at high charge/discharge currents and offering asufficiently high power density of the cell. At the same time, theprocess of the present disclosure allows the production of compositeparticles that exhibit markedly improved mechanical properties whereinthe aggregated primary particles are able to withstand pressure andshear forces applied to the particles during the manufacturing processfor making negative electrodes, for example for lithium-ion batteries.This is due to the fact that the primary particles forming the isotropiccomposite particles are attached to each other through a carbonaceous(graphitic or non-graphitic) binder, as opposed to the mere aggregationof primary particles through van der Waals forces as described in theprior art.

Hence, in this aspect of the disclosure, the process is a multi-stepprocess (although several of the steps can be combined or carried out ina single reactor, as will be explained in greater detail below). Onestep of this process generally comprises the attachment of acarbonaceous binder precursor material to the surface of carbonaceousparticles (“primary particles”), optionally in the presence of asolvent, thereby forming a coating of the carbonaceous particles by thecarbonaceous binder precursor material (“step (a)”). If a solvent wasused in the coating step (a), the dispersion is subsequently dried (byany suitable means) to remove any solvent from the coated particles(“step (b)”). During or after the coating and/or the drying step, theprocess further comprises causing agglomeration of the coated primarycarbonaceous particles (“step (c)”). After agglomeration into compositeintermediate particles formed by a multiplicity of coated primarycarbonaceous particles, the dry agglomerated particles are optionallysubjected to a high temperature treatment between about 1850 and 3500°C. so as to yield carbonaceous composite particles composed of amultiplicity of aggregated primary particles, wherein said primaryparticles are held together by a carbonaceous binder material attachedto the surface of the primary particles (“step (d)”).

In this process, the primary particles are eventually attached to eachother (or “glued” together) by the carbonaceous binder precursormaterial which is converted to a carbonaceous or even graphitic binderduring the heat treatment at temperatures of above 1850° C. up to about3500° C. (the latter is for practical and economic reasons a reasonableupper limit for the maximum temperature during the heating step).

As apparent from the general description of the process, this processcan be characterized as a “retrosynthetic” or “bottom-up” process forconstructing highly desirable isotropic graphitic (or non-graphitic)composite particles with a number of desired properties that can beinfluenced or fine-tuned by the appropriate choice of starting materialsand process parameters/conditions, as explained in greater detail hereinbelow.

Although not limited to such particles, the carbonaceous compositeparticles obtained by the process of the present disclosure will in mostembodiments be characterized by the parameters as described herein aboveor in the appended claims.

Typically, the carbonaceous particles employed in the coating step(“step (a)”) can be selected from the group consisting of naturalgraphite, synthetic graphite, graphene, graphene or carbon fibers,fullerenes, nanographite, hard carbon, soft carbon, petroleum- orcoal-based coke, graphitized fine coke, char, carbon black, carbonnanotubes (CNT), including single-walled nanotubes (SWNT), multiwallednanotubes (MWNT), or mixtures of any of the foregoing. In certainembodiments, non-carbonaceous materials such as silicon, silicon oxide,tin, tin oxide or tin dioxide, aluminum, bismuth, lithium titanate, ormixtures of any of the foregoing may also be added in particulate formto the carbonaceous primary particles (“non-homogenous mixture ofprimary particles”).

As explained above, particularly good results in terms of their isotropyhave been achieved with primary particles that have less anisotropy thannatural graphite flakes. Accordingly, in certain embodiments, thecarbonaceous particles employed in step (a) are non-graphitic particles,preferably selected from the group consisting of hard carbon, softcarbon, petroleum- or coal-based coke, graphitized fine coke, char,carbon black and mixtures thereof. In some particularly preferredembodiments, the carbonaceous particles to be coated are selected fromfine petroleum- or coal-based coke, carbon black; optionally mixedtogether with graphitic particles.

The particle size distribution of the carbonaceous particles employed instep (a) is in most embodiments characterized by a D₉₀ of <35 μm, or <30μm, or <25 μm, or <20 μm, and/or by a D₅₀ of <about 20 μm, <about 15 μm,or <about 10 μm. In order to obtain composite particles that do notexceed a D₅₀ of about 20 to 25 μm, the D₉₀ of the primary particlesshould be <about 20 μm, and/or the D₅₀ should be <about 15 μm.

In terms of the shape or morphology of the primary particles, thecarbonaceous particles to be coated in step (a) may exhibit in someembodiments a sphericity Q3 [S=0.8] of equal or more than 22%, or morethan about 30%, 40%, 50%, i.e. more than e.g. 22% of the primaryparticles have a sphericity of at least 0.8, as determined by dynamicimaging (see Methods section for details on how this parameter isdetermined).

The term carbonaceous binder precursor material in the present contextshould be understood to encompass any suitable carbon-containingmolecule that upon heating in an inert atmosphere can be converted topure non-graphitic or graphitic carbon.

Thus, the carbonaceous binder precursor material to be used in step (a)of the process is in some embodiments selected from the group consistingof polymers, such as a lignin-based polymer, a polystyrene or derivativethereof, a styrene-butadiene copolymer, melted phenol resin,polyvinylalcohol, polyfurfuryl alcohol, furfural, polyurethane,polystyrene-acrylate, polyacrylate, polymethylmethacrylate,polymethacrylonitrile, polyoxymethylene, poly(methyl atropate),polyisobutene, polyethyleneoxide, polypropyleneoxide, polyethylene,polypropylene, polymethylacrylate, polybutadiene, polyisoprene,polyacrylonitrile, polyaniline, tannic acid, starch, gum arabic,maltodextrin, formaldehyde phenol resins, formaldehyde tetrahydrofuranresins, nitrile butyl rubber, sucrose, glucose, or other sugars,polyethyl ether ketone, polyphenylene sulfide, polyvinyl chloride,carboxymethylcellulose, methyl cellulose, gelatins, polyvinylpyrrolidone, polylactic acid, latexes thereof, a hydrocarbon gas such asmethane, ethane, ethylene, propane, propene, acetylene, butane, benzene,toluene, xylene, or an alcohol such as ethanol, propanol, isopropanol(optionally mixed with an inert carrier gas), and combinations thereof.It will be understood that the choice of suitable carbonaceous binderprecursor material also depends on the technique to coat, i.e. attachthe binder precursor material, to the surface of the primarycarbonaceous particles, as detailed below.

While in general not being limited in terms of its weight ratio, theamount of carbonaceous binder precursor material relative to the amountof the carbonaceous primary particles is typically below 30% (w/w), e.g.about 15 to 18%. In some embodiments, the amount of binder precursormaterial is about 18%, or about 15%, or below about 15%, or below about14%, or below about 12% or below about 10%, or below about 5% (w/w) ofthe amount of carbonaceous primary particles to be coated with thebinder precursor material. The inventors have found that it is possibleto achieve the desired result of producing mechanically stable, highlyisotropic aggregate particles by using a relatively low amount of binderthat is apparently sufficient to stably connect the primary particleswith each other upon conversion of the binder precursor material tocarbon or graphite (see working examples where the amount of binderprecursor material was about 15% to 18% (w/w)).

In any event, the carbonaceous binder precursor material used in step(a) of the process in some embodiments is not or does not includeammonium lignosulfonate. In other embodiments, the carbonaceous binderprecursor material used in step (a) of the process is not or does notinclude coal tar, tar pitch, and petroleum pitch, and, optionally alsono ammonium lignosulfonate. Substances like coal tar, tar pitch, andpetroleum pitch could from a technical point of view be used in theprocess of the present disclosure, but they are clearly undesirablesince they are known or suspected to be carcinogenic or hazardoussubstances that should be avoided whenever possible.

Any suitable method to attach the carbonaceous binder precursor materialto the surface of the primary carbonaceous particles can be used in thecontext of the present disclosure. In certain embodiments, suitablemethods to attach the carbonaceous binder precursor material to thesurface of the carbonaceous primary particles include but are notlimited to the following methods selected from the group consisting of

(i) mixing to form a dispersion, optionally in the presence of a solventand subsequent drying;(ii) melting the carbonaceous binder precursor onto the primaryparticles;(iii) pyrolysis; and(iv) evaporation.

In some embodiments, it is preferred that the coating is accomplished bymixing the carbonaceous primary particles with the carbonaceous binderprecursor material to form a dispersion. Preferably, the mixing iscarried out in the presence of a solvent.

The solvent is typically a polar solvent. The solvent may in someembodiments be selected from water, methanol, ethanol, propanol,isopropanol, acetone, or mixtures thereof, with water being particularlypreferred due to its environmentally friendly, non-hazardous properties.

In other embodiments, the carbonaceous binder precursor material mayalso be melted on the carbonaceous particles, which may be accomplishedby heating the mixture of carbonaceous particles and the carbonaceousbinder precursor material until the precursor material melts and adheresto the surface of the carbonaceous particles, thereby forming a coatingon the surface of the carbonaceous primary particles.

If desired, further additives can in some embodiments be added duringstep (a).

Suitable additives may include but are not limited to citric acid,ammonia, acetic acid, formic acid, malic acid, stearic acid, orcombinations thereof.

As noted above, when the coating step (a) includes a solvent, thesolvent must be removed before converting the carbonaceous binderprecursor material attached to the surface of the primary particles. Asa first step, it is often useful to simply filter off the dispersion(comprising the coated primary particles) to remove the bulk of thesolvent. Any residual solvent can in principle be removed by suitable,well-known techniques for removing solvent. Suitable techniques includewell-known drying methods such as freeze-drying, evaporation in aregular atmosphere, or evaporation under a reduced pressure/vacuum,optionally at elevated temperatures, or drying in an optionally heatedinert gas stream.

While the drying step is optional and by definition linked to thepresence of a solvent in step (a), the subsequent agglomeration of thecoated primary particles is at any rate a mandatory key feature of theprocess of the present disclosure.

In general, any suitable method to achieve agglomeration of the primaryparticles can be used in step (c) of the process described and claimedherein. It will be understood that the process of agglomeration of theprimary particles can take place already during the mixing of binderprecursor material and carbonaceous particles, or, in case a solvent isused, it can be achieved during the drying step to remove any residualsolvent. However, agglomerates can also be formed after the mixing andoptional drying steps (steps (a) and (b), respectively) by any suitabletechnique known in the prior art.

One well-known suitable technique to achieve agglomeration of primary(coated) particles is the spray-drying of a dispersion comprising theprimary carbonaceous particles and the carbonaceous binder precursormaterial.

Adjusting the spray-drying conditions allows varying the particle sizeof the final particles prior to the subsequent heat treatment steps. Inthis regard, the spray formation and consequent contact of the dropletswith the hot air in the chamber are its main characteristics. It wasfound that the size of the droplets created during the atomization stepas well as the solvent evaporation rate correlate strongly with theparticle size of the final product. The hot air flow is typicallyco-current which ensures that the spray evaporation is rapid and thedried product does not experience any significant heat degradation. Oncethe solvent fully evaporates from the droplets, the dried product isentrained in the hot air flow from which it can be separated, forexample by a cyclone. The process parameters such as inlet temperature,outlet temperature, pump speed, and gas flow for atomization, of thespray dryer can be optimized individually, depending on the desiredcharacteristics of the particles, as is well-known to those of skill inthe art. Further details, such as suitable devices and processconditions, are described in more detail in the working examples below.

Additional information can also be taken from PCT/EP2015/058112 which isincorporated by reference in its entirety.

However, the drying of step (b) and the agglomeration of step (c) may insome embodiments also be achieved by vacuum-drying a dispersioncomprising the primary carbonaceous particles and the carbonaceousbinder precursor material obtained from step (a) in a heatable vacuumreactor. This drying process will automatically lead to suitableagglomerates, provided the particle size distribution of the primaryparticles allows their agglomeration under the chosen drying conditions.

Alternatively, the drying of step (b) and the agglomeration of step (c)may be achieved by freeze-drying a dispersion comprising the primarycarbonaceous particles and the carbonaceous binder precursor materialobtained from step (a) in a stirred freeze dryer.

The drying of step (b) and the agglomeration of step (c) may in certainembodiments be also achieved by flash-drying a dispersion comprising theprimary carbonaceous particles and the carbonaceous binder precursormaterial obtained from step (a) in a flash dryer.

Yet another possible way to accomplish the drying of step (b) and theagglomeration of step (c) is by drying a fluidized dispersion comprisingthe primary carbonaceous particles and the carbonaceous binder precursormaterial obtained from step (a) in a fluidized bed dryer, optionally incombination with a spray system.

The drying of step (b) and the agglomeration of step (c) may also beachieved by disc drying a dispersion comprising the primary carbonaceousparticles and the carbonaceous binder precursor material obtained fromstep (a) in a disc dryer.

Alternatively, the drying of step (b) and the agglomeration of step (c)may be achieved by paddle drying a dispersion comprising the primarycarbonaceous particles and the carbonaceous binder precursor materialobtained from step (a) in a paddle dryer.

The drying of step (b) may in some embodiments also include thefiltering of the dispersion comprising the primary carbonaceousparticles and the carbonaceous binder precursor material obtained fromstep (a) and drying the resulting filtered cake in one of the suitabledryers mentioned above.

The carbonaceous binder precursor material attached to the surface ofthe agglomerated particles obtained from step (c) is then, if necessary,carbonized by subjecting the particles to a heat treatment under vacuumor an inert atmosphere, optionally under a nitrogen or argon atmosphere,at temperatures generally ranging from 400° C. to 3500° C., therebycausing a thermal decomposition of the precursor material. Temperaturesof about 400° C. to 600° C. are generally regarded as sufficient tocarbonize any carbonaceous precursor material present on the surface ofthe primary particles, although higher temperatures will likewiseconvert the precursor material to amorphous carbon or, at temperaturesabove about 2000° C., to graphitic carbon.

It is therefore apparent that the carbonization of the precursor may becarried out in a separate heat treatment step prior to step (d), or itmay be carried out as part of the heat treatment step (d) with acontrolled ramp up of the temperatures in the reactor. In addition, itwill be understood that since the agglomeration step (c) may already useheating, steps (c) and (d) (and possibly also step (b), i.e. drying ofthe dispersion) may in some embodiments also be carried outsimultaneously.

For example, a suitable heating scheme may include heating theagglomerated particles under vacuum or in an inert atmosphere first upto 400 to 800° C., keeping the particles at that temperature for asufficient time to carbonize the precursor material and to remove anygases from the thermal decomposition of the precursor material, followedby increasing the temperature to above 1850° C. (and up to 3500° C.) andkeeping the particles for a sufficient time to convert at least aportion of any amorphous carbon derived from the precursor material tographitic carbon. Alternatively, the carbonization can also be carriedout in a separate step and/or a separate reactor.

In any event, it is in certain embodiments preferred to first carbonizethe precursor material at lower temperatures of between 400° C. to 800°C. to allow the complete removal of any gases generated by the thermaldecomposition of the precursor material, before heating the agglomeratedparticles to temperatures above 1850° C. to obtain the stable, highlyisotropic composite particles composed of aggregated primary particlesconnected to each other by the non-graphitic or graphitic binder.

In some embodiments of this aspect of the disclosure, it is preferredthat the heat treatment of step (d) is carried out at temperatures andfor a sufficient time to convert any non-graphitic carbon in theintermediary agglomerated particles obtained from step (c) to graphiticcarbon. In other embodiments, the heating step (d) will not convert allamorphous carbon to graphitic carbon. In both cases, particlesexhibiting favorable electrochemical and mechanical properties have beenobtained.

The process may in certain embodiments encompass a pre-treatment stepprior to the heat treatment step (d), wherein the coated agglomeratedcarbonaceous particles are subjected to a pre-treatment performed undervacuum, air, nitrogen, argon or a CO₂ atmosphere at temperatures ofbelow 1100° C., or below 700° C. to modify the surface of theagglomerated particles.

In yet other embodiments, the process may also include an additionalheat treatment step (“post-treatment step”) after step (d). In thispost-treatment step, the composite particles obtained from step (d) aresubjected to an additional heat treatment in a gas atmosphere such asnitrogen, argon, mixtures of nitrogen with hydrocarbons like acetylene,propane or methane, or with oxidative gases such as air, steam, or CO₂to adjust the morphology and surface chemistry of the carbonaceouscomposite particles. The post-treatment is typically carried out attemperatures of between 300° C. and 1500° C. In some embodiments, thisadditional heat treatment step (“post-treatment step”) is performed bycontacting the composite particles with an oxidant either in agaseous/solid phase process with air, carbon dioxide, water vapor,oxygen, ozone, or any combination thereof, or, alternatively, in aliquid/solid phase process with aqueous hydrogen peroxide or otheroxidants present in said liquid phase. Such a post-treatment may forexample be employed in order to increase the hydrophilicity of theresulting particles. Further information on the aforementionedpost-treatment steps may for example be found in WO 2013/149807 or inPCT/EP2015/066212, both to Imerys Graphite & Carbon, which areincorporated by reference in their entirety.

Another possible post-treatment step (i.e. after step (d)) may in someembodiments include an additional coating step of the resultingcomposite particles, such as a CVD coating or a PVD coating and thelike. It is readily apparent that a subsequent coating with an amorphouscarbon layer will change the surface characteristics of the resultingcomposite particles (in the case of CVD coating for example a lower BETSSA, lower porosity, a lower surface crystallinity, etc.).

In a particularly preferred embodiment, the process is carried out withfine (D₉₀ below 20 μm and a D₅₀ of below 10 μm) non-graphiticcarbonaceous particles as a starting material. Such non-graphiticparticles (e.g. fine coke or carbon black) are already less anisotropicthan graphite particles. These particles are then coated with acarbonaceous binder precursor material in the presence of a solvent. Theresulting dispersion is subsequently spray-dried to cause removal of thesolvent and agglomeration of the primary, coated particles. The obtainedagglomerated intermediate particles are then subjected to a heattreatment, first at around 400 to 600° C. and then to a heat treatmentat above 1850° C. in order to generate the carbonaceous (and in manyinstances at least partially graphitic) composite particles describedherein. Such a process is for example described in further detail in theExamples below.

The resulting carbonaceous composite particles obtained by the processdescribed herein exhibit favorable electrochemical and mechanicalproperties as explained above.

Accordingly, a further aspect of the present invention therefore relatesto carbonaceous composite particles as described herein which areobtainable by a process according to the present invention, as describedin detail in the present disclosure. The carbonaceous compositeparticles obtainable from the process of the invention are in someembodiments characterized by the parameters as set out herein above andin the appended claims.

Compositions Comprising Carbonaceous Composite Particles

Another aspect of the present invention relates to compositionscomprising said carbonaceous composite particles. In some embodiments ofthis aspect, the composition comprises mixtures of carbonaceouscomposite particles, wherein the particles are different from eachother, e.g. made by a different process or with different startingmaterials. The compositions may in other embodiments furthermore, oralternatively, comprise other unmodified (e.g. natural or syntheticgraphite) or modified carbonaceous, e.g. graphitic or non-graphiticparticles. Thus, in other words, compositions comprising carbonaceouscomposite particles according to the present disclosure with othercarbonaceous or non-carbonaceous materials, in various ratios (e.g. from1:99 (% w/w) to 99:1 (% w/w)) are also contemplated by the presentdisclosure. In certain embodiments, unmodified graphite may be added tothe carbonaceous composite particles at various stages of making theproducts described herein.

Uses and Secondary Products Comprising the Carbonaceous CompositeParticles

Yet another aspect of the present invention relates to the use of thecarbonaceous composite particles or the composition comprising saidcarbonaceous composite particles as described herein for preparing anegative electrode material for lithium-ion batteries. Another, relatedaspect of the present disclosure relates thus to a negative electrode ofa lithium-ion battery and/or to a lithium-ion battery comprising thecarbonaceous composite particles or the composition comprising saidcarbonaceous composite particles as described herein as an activematerial in the negative electrode of the battery. For instance, acomposition comprising a binder and the carbonaceous composite particlesor the composition comprising said carbonaceous composite particles asdescribed herein could be used to produce a negative electrode.

In yet another aspect, the present disclosure relates to an energystorage device comprising the carbonaceous composite particles or thecomposition comprising said carbonaceous composite particles asdescribed herein.

A further aspect of the present disclosure relates to a carbon brushcomprising the carbonaceous composite particles or the compositioncomprising said carbonaceous composite particles as described herein.

Polymer composite materials comprising the carbonaceous compositeparticles or the composition comprising said carbonaceous compositeparticles as described herein represent another aspect of the presentdisclosure.

An electric vehicle, hybrid electric vehicle, or plug-in hybrid electricvehicle which comprises a lithium-ion battery, wherein the lithium-ionbattery comprises the carbonaceous composite particles or thecomposition comprising said carbonaceous composite particles asdescribed herein as an active material in the negative electrode of thebattery is another aspect of the present disclosure. In some embodimentsof this aspect, the carbonaceous particles comprise only graphiticmaterial, while in other materials the carbonaceous particles may alsocomprise non-graphitic material.

Due to the larger size of sodium ions as compared to lithium-ions,sodium ions typically do not undergo intercalation with graphite, butare rather adsorbed on the carbon surface, especially inside pores witha sufficiently large diameter. The importance of isotropicelectrolyte-filled pores with low tortuosity in order to obtainfavorable sodium-ion diffusion in negative electrodes is howeveranalogous to lithium-ion battery electrodes. Thus, a sodium-ion batterycomprising the carbonaceous composite particles or the compositioncomprising said carbonaceous composite particles as described hereinrepresents another aspect of the present invention.

Yet another aspect of the present disclosure relates to a carbon-basedcoating exhibiting isotropic electric, mechanical or heat-conductingproperties, wherein said coating comprises the carbonaceous compositeparticles or the composition comprising said carbonaceous compositeparticles as described herein. A related aspect thus refers to the useof said carbon-based coating as a coating of current collectors inbatteries.

Dispersions comprising the carbonaceous composite particles or thecomposition comprising said carbonaceous composite particles asdescribed herein are yet another aspect of the present disclosure. Suchdispersions are typically liquid solid dispersions, i.e. they alsoinclude a solvent. Suitable solvents may in some embodiments includewater, or N-methyl-2-pyrrolidone (NMP), both commonly used as solventsfor carbon-based dispersions.

Finally, the present disclosure relates to a method for preparing abuilding block of a negative electrode, employing the carbonaceouscomposite particles or the composition comprising said carbonaceouscomposite particles as described herein. Given that the compositeparticles already have a near optimal shape and pore distribution, theuse of the carbonaceous composite particles as described herein in themanufacture of negative electrodes allows dispensing additional stepsthat must otherwise be included to ensure that the graphite particles inthe electrode are distributed in an isotropic fashion (i.e. avoiding apreferred orientation in case of conventional anisotropic graphiteparticles). The composite particles therefore represent a“pre-fabricated” building block that can be used in the manufacture ofnegative electrodes for lithium-ion batteries.

The concept of preparing a building block for a negative electrode thatexhibits both, favorable energy density and favorable charge/dischargeperformance at C-rates of 2 C (i.e. a charge/discharge within 30 min) orfaster was further developed by preparing “snowball” carbon powdersbased on both coke and graphite (cf. Example 4 and Table 4 below) asprecursor material. The latter allows the fine-tuning of the pore sizedistribution in order to achieve an optimal Li-diffusion in theelectrode, as indicated by the characterization of the materials throughmercury porosimetry.

Furthermore, it was demonstrated that mixing such snowball carbonpowders with high capacity but less spherical graphitic active materials(e.g. 30% snowball carbon powder and 70% high capacity graphite, seeExample 4), leads to a dramatic power performance increase (cf. Table5). Accordingly, by mixing snowball carbon powders with high capacitygraphites, energy density, power performance as well as production costscan be favorably adjusted to specific applications, such as automotivebatteries (employed in electric vehicle, hybrid electric vehicle, orplug-in hybrid electric vehicle), grid storage batteries, or batteriesfor other applications.

Methods BET Specific Surface Area (BET SSA)

The method is based on the registration of the absorption isotherm ofliquid nitrogen in the range p/p₀=0.04-0.26, at 77 K. Following theprocedure proposed by Brunauer, Emmet and Teller (Adsorption of Gases inMultimolecular Layers, J. Am. Chem. Soc., 1938, 60, 309-319), themonolayer adsorption capacity can be determined. On the basis of thecross-sectional area of the nitrogen molecule, the monolayer capacityand the weight of the sample, the specific surface area can then becalculated.

BET Specific Surface Area after Pressing at 15 kN/cm²

The BET Specific Surface Area is measured as described above afterpressing the powder sample in a piston with a press force of 15 kN/cm²for 10 s (pressing ramp duration: 5 s). More specifically, 0.5 g of agraphite/carbon powder sample were inserted between 2 steel discs into apellet press (PIKE Technologies, USA) with a cylindrical hole diameterof 13 mm. The steel piston (PIKE Technologies, USA) was inserted intothe cylindrical hole. With a hydraulic press (P/O/Weber, Germany) anautomatic protocol was run as follows:

1) increase press force from 0 kN to 20 kN (15 kN/cm²) over the courseof 5 s;2) keep press force constant at 20 kN for 10 s;3) decrease press force from 20 kN to 0 kN over the course of 5 s.After completion of the protocol and repetition of the procedure inorder to obtain sufficient material, the BET specific surface area ofthe powder was measured as described above.

X-Ray Diffraction

XRD data were collected using a PANalytical X′Pert PRO diffractometercoupled with a PANalytical X'Celerator detector. The diffractometer hasthe following characteristics shown in Table 1:

TABLE 1 Instrument data and measurement parameters InstrumentPANalytical X'Pert PRO X-ray detector PANalytical X'Celerator X-raysource Cu—K_(α) Generator parameters 45 kV-40 mA Scan speed 0.07°/s (forL_(c) and c/2) 0.01°/s (for [004]/[110] ratio) Divergence slit 1° (forL_(c) and c/2) 2° (for [004]/[110] ratio) Sample spinning 60 rpm

The data were analyzed using the PANalytical X′Pert HighScore Plussoftware.

Interlayer Spacing c/2

The interlayer space c/2 is determined by X-ray diffractometry. Theangular position of the peak maximum of the [002] and [004] reflectionprofiles are determined and, by applying the Bragg equation, theinterlayer spacing is calculated (Klug and Alexander, X-ray DiffractionProcedures, John Wiley & Sons Inc., New York, London (1967)). To avoidproblems due to the low absorption coefficient of carbon, the instrumentalignment and non-planarity of the sample, an internal standard, siliconpowder, is added to the sample and the graphite peak position isrecalculated on the basis of the position of the silicon peak. Thegraphite sample is mixed with the silicon standard powder by adding amixture of polyglycol and ethanol. The obtained slurry is subsequentlyapplied on a glass plate by means of a blade with 150 μm spacing anddried.

Crystallite Size L_(c)

Crystallite size is determined by analysis of the [002] and [004] X-raydiffraction profiles and determining the widths of the peak profiles atthe half maximum. The broadening of the peak should be affected bycrystallite size as proposed by Scherrer (P. Scherrer, GöttingerNachrichten 2, 98 (1918)). However, the broadening is also affected byother factors such X-ray absorption, Lorentz polarization and the atomicscattering factor. Several methods have been proposed to take intoaccount these effects by using an internal silicon standard and applyinga correction function to the Scherrer equation. For the presentdisclosure, the method suggested by Iwashita (N. Iwashita, C. Rae Park,H. Fujimoto, M. Shiraishi and M. Inagaki, Carbon 42, 701-714 (2004)) wasused. The sample preparation was the same as for the c/2 determinationdescribed above.

[004]/[110] ratio

The isotropicity of the crystallites is determined by the ratio of theintensity and/or by the ratio of the area between the [004] and the[110] XRD peaks. The intensity and the area of the peaks are determinedafter applying a peak fitting program using the PANalytical X′PertHighScore Plus software. The samples are prepared as a slurry on a Mylarfoil which is then dried. During the blading of the slurry on the foil,an alignment of flaky particles occurs. Through this blading procedure,a preferred orientation of anisotropic particles such as graphite isintroduced.

If crystallites are arranged in an anisotropic fashion on the Mylarfoil, the [004]/[110] ratio of the peak areas is very high (i.e. in apreferred orientation). By contrast, if crystallites are orientedrandomly, the [004]/[110] ratio is low. Ratios are reported based onpeak area and intensity.

Crystallite Size L_(a) by Raman Spectroscopy

Raman analyses were performed using a LabRAM-ARAMIS Micro-RamanSpectrometer from HORIBA Scientific with a 632.8 nm HeNe LASER. Theratio I_(G)/I_(D) is based on the ratio of peak amplitudes of band D andband G. These peaks are characteristic for carbon materials, measured at1580 cm⁻¹ and 1350 cm⁻¹, respectively.

Crystallite size L_(a) is calculated from Raman measurements using theequation

L _(a)[nm]=C*(I _(G) /I _(D)),

where the constant C has a value of 5.8 nm for lasers with a wavelengthof 632.8 nm (A. C. Ferrari, Solid State Comm. 2007, 143, 47-57).

Particle Size Distribution by Laser Diffraction

The presence of particles within a coherent light beam causesdiffraction. The dimensions of the diffraction pattern are correlatedwith the particle size. A parallel beam from a low-power laser isirradiated on a cell which contains the sample suspended in water. Thebeam leaving the cell is focused by an optical system. The distributionof the light energy in the focal plane of the system is then analyzed.The electrical signals provided by the optical detectors are transformedinto the particle size distribution by means of a calculator. A smallsample of graphite is mixed with a few drops of wetting agent and asmall amount of water. The sample prepared in the described manner isintroduced into the storage vessel of the apparatus and measured.

References: ISO 13320-1/ISO 14887 Xylene Density

The analysis is based on the principle of liquid exclusion as defined inDIN 51 901. Approx. 2.5 g (accuracy 0.1 mg) of powder is weighed in a 25ml pycnometer. Xylene is added under vacuum (20 mbar). After a few hoursdwell time under normal pressure, the pycnometer is conditioned andweighed. The density represents the ratio of mass and volume. The massis given by the weight of the sample and the volume is calculated fromthe difference in weight of the xylene filled pycnometer with andwithout sample powder.

Reference: DIN 51 901 Scott Density (Apparent Density)

The Scott density is determined by passing the dry carbon powder throughthe Scott volumeter according to ASTM B 329-98 (2003). The powder iscollected in a 1 in 3 vessel (corresponding to 16.39 cm³) and weighed to0.1 mg accuracy. The ratio of weight and volume corresponds to the Scottdensity. It is necessary to measure three times and calculate theaverage value. The bulk density of graphite is calculated from theweight of a 250 mL sample in a calibrated glass cylinder.

Reference: ASTM B 329-98 (2003) Spring-Back

Spring-back is a source of information regarding the resilience ofcompacted graphite powders. A defined amount of powder is poured into adie. After inserting the punch and sealing the die, air is evacuatedfrom the die. A compression force of about 1.5 tons/cm² is applied andthe powder height is recorded. This height is recorded again after thepressure has been released. Spring-back is the height difference inpercent relative to the height under pressure.

Mercury Intrusion Porosimetry

The method is based on the measurement of the amount of mercuryintrusion versus the pressure applied to a sample immersed in mercury.On the basis of the applied pressure, the surface tension of mercury andthe contact angle between mercury and the solid surface, the pore sizecan be calculated. The experiments were performed on a sample (ca.0.1-0.3 g) over the pressure range of 0.5-4000 bar using a MicromeriticsAutopore III machine. For treating the data, a contact angle of 130° anda surface tension of 485×10⁻³ N/m were used. The porosity of a sample isdetermined from the following equation:

${Porosity} = \frac{{Specific}\mspace{14mu} {pore}\mspace{14mu} {volume}}{{{Specific}{\; \mspace{11mu}}{pore}\mspace{14mu} {volume}} + {1\text{/}{xylene}\mspace{14mu} {density}}}$

where the specific pore volume is determined as the volume of mercuryintruded per gram of sample, including interparticle and intraparticleporosity. The volume of mercury which causes the initial settling of thesample due to the exerted pressure is not included. Reference: ISO15901-1:2005(E)

Thermogravimetric Analysis (TGA)

The determination of the percentage of mass loss of any pyrolyzed carbonis performed by using conventional thermogravimetric equipment (TGA). Asample of ca. 20-30 mg was used for the measurements. The atmosphere inthe thermogravimetric equipment is pure oxygen with a flow rate of 10mL/min (with initial purging of 30 mL/min) with a heating rate of 5°C./min up to 1000° C. followed by an isotherm of 2 hours. Pyrolyzedcarbon can be distinguished from graphitic or non-graphitic carbon as itburns off at lower temperature.

Dynamic Image Analysis

The sphericity and the aspect-ratio of the particles of the materialwere obtained from an image analysis sensor, which is a combination ofparticle size and shape analysis. The experiments were performed using aSympatec QICPIC sensor and a MIXCEL dispersing unit. The material wasprepared as a paste with water and a surfactant (liquid detergent). Theinstrument uses a high speed camera (up to 500 fps) and a pulsed lightsource to capture clear rear-illuminated images of entrained particles.The measurement time varied between 30-60 seconds with an average ofmore than 500000 measured particles. Each sample was repeated threetimes for reproducibility measurements. The software program determinesall of the parameters for the particles.

Sphericity

The sphericity, S, is the ratio of the perimeter of the equivalentcircle (assuming the particles are circles with a diameter such that ithas the same area of the projection area of the particle), P_(EQPC), tothe real perimeter, P_(real). The Q₃ (S=0.8) value mentioned hereincorresponds to the percentage of particles (by cumulative volume) whichhave a sphericity lower than S=0.8. Accordingly, a small percentageindicates a sample with highly spherical particles as the majority ofthe particles in the sample have a sphericity greater than 0.8.

Additionally, k_(S,ρ) is a parameter expressing the ratio of thepercentage Q₃ (S=0.8) versus the decrease in xylene density from thetheoretical value for graphite (which is 2.26 g/cm³):

k _(S,ρ) =Q ₃(S=0.8)/(2.26−xylene density)

For non-graphitic (coke) particles coated with amorphous carbon, k_(S,ρ)is a parameter expressing the ratio of the percentage Q₃ (S=0.8) versusthe decrease in xylene density from the value observed for averageuncoated coke particles (which is 2.1 g/cm³):

k _(S,ρ) =Q ₃(S=0.8)/(2.1−xylene density)

PAH Concentration

The concentration of polycyclic aromatic hydrocarbons PAH was determinedby the Grimmer method and the analyses were performed externally byBIU-Grimmer (Germany). The Grimmer method generally used for PAHanalysis is based on a stable isotope dilution methodology usingGC-MS(SIM) for quantification in the sub ppb range.

Lithium-Ion Negative Electrode Half Cell Test—Standard Procedure

This test was used to quantify the reversible and irreversible capacityof the surface-modified coated carbonaceous particles.

General Half-Cell Parameters:

2 Electrode coin cell design with Li metal foil as counter/referenceelectrode, cell assembly in an argon filled glove box (oxygen and watercontent <1 ppm).

Diameter of Electrodes:

13 mmA calibrated spring (100 N) was used in order to have a defined force onthe electrode. Tests were carried out at 25° C.

Dispersion Formulation:

97% graphite/coke, 1% CMC (Sodium-carboxymethylcellulose), 2% SBR(styrene-butadiene rubber)

Dispersion Preparation:

Add the carbon powder to the CMC solution (1.5% in water) and homogenizewith a dissolver disk for 20 min at reduced pressure at 600 rpm. Add theSBR latex (46% in water) and further homogenize for 20 min.

Blading Height on Cu Foil:

200 μm (doctor blade).

Drying Procedure:

Coated Cu foils were dried for 1 h at 80° C., followed by 12 h at 120°C. under vacuum (<50 mbar). After cutting, the electrodes were dried for10 h at 120° C. under vacuum (<50 mbar) before insertion into the glovebox.

Pressing of Electrodes:

As indicated in Tables 3 and 4, electrodes were either measured withoutpressing, or were pressed to a density of 1.5-1.7 g/cm³ using ahydraulic press.

Electrolyte:

Ethylenecarbonate (EC): Ethylmethylcarbonate (EMC) 1:3, 1 M LiPF₆ wasused for all examples.

Separator:

Glass fiber sheet, ca. 1 mm.

Cycling Program Using a Potentiostat/Galvanostat:

1^(st) charge: constant current step 20 mA/g to a potential of 5 mV vs.Li/Li⁺, followed by a constant voltage step at 5 mV vs. Li/Li′ until acutoff current of 5 mA/g was reached.1^(st) discharge: constant current step 20 mA/g to a potential of 1.5 Vvs. Li/Li⁺, followed by a constant voltage step at 1.5 V vs. Li/Li′until a cutoff current of 5 mA/g was reached.2^(nd) charge: constant current step at 50 mA/g to a potential of 5 mVvs. Li/Li⁺, followed by a constant voltage step at 5 mV vs. Li/Li′ untila cutoff current of 5 mA/g was reached.2^(nd) discharge: constant current step at 3 C to a potential of 1.5 Vvs. Li/Li⁺, followed by constant voltage step at 1.5 V vs. Li/Li′ untila cutoff current of 5 mA/g was reached.

Power Performance

2 C was applied to the fully charged cell to a potential of 1.5V vs.Li/Li⁺. The power performance was defined as the obtained capacitydivided by the reversible capacity of the 2^(nd) cycle.

Having described the various aspects of the present disclosure ingeneral terms, it will be apparent to those of skill in the art thatmany modifications and slight variations are possible without departingfrom the spirit and scope of the present disclosure.

Some of these embodiments will now also be described by way ofillustration, with reference to the following examples.

EXAMPLES Example 1

30 g of ammonium lignosulfonate were dissolved in 600 mL of deionizedwater while stirring vigorously with a dissolver disc. 200 g of cokeprecursor 1 (properties listed in Table 1 below) were slowly added,followed by further mixing for 2 h. This dispersion was spray-driedusing a Büchi B-290 laboratory spray dryer, using a 2-fluid nozzle inco-current mode with an inlet temperature of 170° C. and an air gas flowrate of 700 L/h, resulting in a carbonaceous powder that was collectedin the product collection vessel attached to the cyclone. In a glasstube carbonization oven, this powder was heated to 450° C. under anitrogen atmosphere over the course of 1 h, followed by furthertreatment at 450° C. for 1 h. Heat treatment in an argon atmosphere(ramp up to 2′000° C.: 10° C./min, ramp from 2′000-3′000° C.: 5° C./min,followed by 4 h at 3′000° C.) resulted in carbon powder 4 (see Table 2).

Example 2

30 g of ammonium lignosulfonate were dissolved in 600 mL of deionizedwater while stirring vigorously with a dissolver disc. 200 g of cokeprecursor 2 (properties listed in Table 1 below) were slowly added,followed by further mixing for 2 h. This dispersion was spray-driedusing a Büchi B-290 laboratory spray dryer, using a 2-fluid nozzle inco-current mode with an inlet temperature of 170° C. and an air gas flowrate of 700 L/h, resulting in a carbonaceous powder that was collectedin the product collection vessel attached to the cyclone. In a glasstube carbonization oven, this powder was heated to 450° C. under anitrogen atmosphere over the course of 1 h, followed by furthertreatment at 450° C. for 1 h. Heat treatment in an argon atmosphere(ramp up to 2′000° C.: 10° C./min, ramp from 2′000-3′000° C.: 5° C./min,followed by 4 h at 3′000° C.) resulted in carbon powder 6 (see Table 2).Alternatively, heat treatment after carbonization at 450° C. in an argonatmosphere (ramp up to 1′800° C.: 10° C./min, followed by 4 h at 1′800°C.) resulted in carbon intermediate 5 (see Table 2).

Example 3

30 g of ammonium lignosulfonate were dissolved in 600 mL of deionizedwater while stirring vigorously with a dissolver disc. 200 g of cokeprecursor 3 (properties listed in Table 1 below) were slowly added,followed by further mixing for 2 h. This dispersion was spray-driedusing a Büchi B-290 laboratory spray dryer, using a 2-fluid nozzle inco-current mode with an inlet temperature of 170° C. and an air gas flowrate of 700 L/h, resulting in a carbonaceous powder that was collectedin the product collection vessel attached to the cyclone. In a glasstube carbonization oven, this powder was heated to 450° C. under anitrogen atmosphere over the course of 1 h, followed by furthertreatment at 450° C. for 1 h. Heat treatment in an argon atmosphere(ramp up to 2′000° C.: 10° C./min, ramp from 2′000-3′000° C.: 5° C./min,followed by 4 h at 3′000° C.) resulted in carbon powder 7 (see Table 2).

Example 4

300 g of ammonium lignosulfonate were dissolved in 6′000 mL of deionizedwater while stirring vigorously with a dissolver disc. 1′100 g of cokeprecursor 9 and 600 g of graphite precursor 10 (properties listed inTable 3 below) were slowly added, followed by further mixing for 2 h.This dispersion was spray-dried using a pilot scale spray dryer, using a2-fluid nozzle in co-current mode with an inlet temperature of 220° C.and an air gas pressure of 3 bar, resulting in a carbonaceous powderthat was collected in the product collection vessel attached to thecyclone. In a carbonization oven, this powder was heated to 450° C.under a nitrogen atmosphere over the course of 1 h, followed by furthertreatment at 450° C. for 1 h. Heat treatment in an argon atmosphere(ramp up to 2′000° C.: 10° C./min, ramp from 2′000-3′000° C.: 5° C./min,followed by 4 h at 3′000° C.) resulted in carbon powder 11. Thephysicochemical parameters of carbon powder 11 are shown in Table 4. Inelectrochemical tests, the carbon powder 11 was mixed with graphiteactive material 12 (a synthetic graphite with a hydrophilic coating, asdescribed in WO 2016/008951) in a 3:7 weight ratio, and the mixture wasused to prepare negative electrodes. The electrochemical data for theactive graphite mixture 13 are reported in Table 4 and 5. As shown inFIGS. 5 and 6, the analysis by means of SEM of the cross-sections forthese electrodes shows that the snow-ball morphology of the secondarygraphite particles is essentially maintained even in the pressedelectrode.

Comparative Example 5

Heat treatment of coke precursor 1 (properties listed in Table 1 below)in an argon atmosphere (ramp up to 2′000° C.: 10° C./min, ramp from2′000-3′000° C.: 5° C./min, followed by 4 h at 3′000° C.) resulted incarbon powder 8 (see Table 2).

Results

TABLE 2 Properties of Carbon Precursors Coke Coke Coke precursor 1precursor 2 precursor 3 Particle size D₁₀ (μm) 3.3 2.9 3.8 D₅₀ (μm) 7.86.9 9.0 D₉₀ (μm) 15.0 13.2 16.2 BET SSA 4.7 13.3 19 (m²/g) Xylenedensity 2.13 2.077 1.534 (g/cm³) Scott density 0.22 0.26 0.44 (g/cm³)Interlayer distance c/2 (nm) 0.3486 0.3490 0.3561 Crystallite size L_(c)(nm) 4 2.9 2

TABLE 3 Properties of Carbonaceous Composite Particles Carbon powder 8Carbon Carbon Carbon Carbon (comparative powder 4 intermediate 5 powder6 powder 7 example) Particle size D₁₀ (μm) 7.5 7.6 6.7 n.d. 2.9 D₅₀ (μm)14.9 15.6 14.1 7.5 D₉₀ (μm) 25.9 29.0 26.0 14.1 BET SSA 1.7 2.1 1.9 n.d.2.9 (m²/g) BET SSA 2.4 3.1 2.7 n.d. n.d. (m²/g) after pressing at 15kN/cm² Xylene density 2.254 2.161 2.251 2.029 2.256 (g/cm³) Scottdensity 0.30 n.d. 0.35 n.d. 0.19 (g/cm³) Interlayer 0.3363 0.3482 0.33640.3438 0.3362 distance c/2 (nm) Crystallite size 108 10 86 10 132 L_(c)(nm) Crystallite size 58 4 n.d. n.d. n.d. L_(a) (nm) [004]/[110] 2.08n.d. 1.59 n.d. 147 (intensity) [004]/[110] 3.36 n.d. 2.26 n.d. 180(area) Mass loss of 0.2 n.d. 0.2 0.3 n.d. pyrolyzed carbon (TGA) [%]Reversible 324 n.d. n.d. 181 n.d. capacity 2^(nd) cycle (mAh/g),unpressed electrodes Irreversible 6.3 n.d. n.d. 18.2 n.d. capacity1^(st) cycle [%], unpressed electrodes

TABLE 4 Properties of Carbonaceous Composite Particles based on aCoke/Graphite Precursor Mixture Active Material 13 (mixture of carbonGraphite powder 11 and Coke Graphite Carbon Active material 12 @precursor 9 precursor 10 powder 11 Material 12 weight ratio 3:7)Particle size n.d. D₁₀ (μm) 1.4 2.4 5.6 7.4 D₅₀ (μm) 7.3 6.0 15.5 17.2D₉₀ (μm) 19.7 12.3 33.3 34.9 BET SSA 19.2 15.2 2.1 3.4 n.d. (m²/g) BETSSA n.d. n.d. 2.8 n.d. n.d. (m²/g) after pressing at 15 kN/cm² Xylenedensity 2.052 2.25 2.22 2.217 n.d. (g/cm³) Interlayer 0.3493 0.33580.3365 0.3357 n.d. distance c/2 (nm) Crystallite size 3 99 72 147 n.d.L_(c) (nm) Reversible n.d. n.d. 325 358 347 capacity 1^(st) cycle(mAh/g) Irreversible n.d. n.d. 7.9 8.2    8.3 capacity 1^(st) cycle [%]Hg- n.d. n.d. 69.2 n.d. n.d. porosimetry

Several materials were also examined in terms of their electrochemicalproperties, in particular regarding their specific charge and coulombicefficiency. Specific charge obtained in the first electrochemicallithium insertion and subsequent de-insertion cycle, the coulombicefficiency of the first insertion/de-insertion cycle, the direct currentresistance (DCR) and the high rate performance of the electrode at 2 C(specific charge of the half-cell obtained by a complete discharge in 30minutes) normalized to the specific charge at 0.2 C (5 h discharge).

TABLE 5 Electrochemical Parameters Active Material 13 (mixture of carbonSpherical coated powder 11 and natural graphite Carbon Graphite Activematerial 12 @ (reference material) powder 11 Material 12 weight ratio3:7) Specific charge 1^(st) 392.0 353.1 389.7 377.7 lithium insertion inmAh/g Specific charge 1^(st) 359.8 325.0 357.6 346.5 lithium de-insertion in mAh/g Coulombic 91.8 92.2 91.8 91.7 efficiency (1^(st)charge/discharge cycle) in % DCR in Ohm 19.5 24.2 23.8 26.3 Specificcharge 98.2 99.9 97.5 99.0 retention (rate capability) at 2 C/0.2 C in %

Additionally, the pore volume distribution was determined by mercuryporosimetry for several carbonaceous materials (a synthetic graphite, aspherical natural graphite and carbon powder 11), see also FIG. 8 for agraphical representation of the results.

TABLE 6 Pore Volume Distribution by Mercury Porosimetry >10 μm 5-10 μm1-5 μm 0.1-1 μm Synthetic Graphite 0.3 0 0.7 0 Spherical NaturalGraphite <0.1 0 0.3 0.1 Graphite Powder 11 0.2 0 0.8 0

1-73. (canceled)
 74. A process for preparing carbonaceous compositeparticles, comprising: (a) attaching a carbonaceous binder precursormaterial to the surface of carbonaceous particles in the presence of asolvent, thereby forming a coating of the carbonaceous particles by thecarbonaceous binder precursor material; (b) drying the material obtainedfrom step (a); and (c) during or after step (a) or step (b), causingagglomeration of the coated primary carbonaceous particles.
 75. Theprocess according to claim 74, wherein the carbonaceous compositeparticles are comprised of a multiplicity of aggregated primaryparticles, wherein said primary particles are held together by acarbonaceous binder material attached to the surface of the primaryparticles.
 76. The process of claim 74, wherein the carbonaceous binderprecursor material is not or does not include ammonium lignosulfonate,and is not or does not include coal tar, tar pitch, and petroleum pitch.77. The process according to claim 74, wherein the carbonaceousparticles employed in step (a) are selected from the group consisting ofnatural graphite, synthetic graphite, graphene, graphene nanoplatelets,graphene or carbon fibers, fullerenes, nanographite, hard carbon, softcarbon, petroleum- or coal-based coke, graphitized fine coke, char,carbon black, carbon nanotubes (CNT), including single-walled nanotubes(SWNT), multiwalled nanotubes (MWNT), carbon nanofibers (CNF) ormixtures thereof; or from non-carbonaceous materials such as silicon,silicon oxide, tin, tin oxide or tin dioxide, aluminum, bismuth, lithiumtitanate, or mixtures of any of the foregoing.
 78. The process accordingto claim 74, wherein the carbonaceous particles employed in step (a) arenon-graphitic particles.
 79. The process according to claim 74, whereinthe particle size distribution of said carbonaceous particles employedin step (a) is characterized by at least one of: i) a D90 of <35 μm, ii)a D50 of <about 20 μm, iii) a D90 of <25 μm, and iv) a D50 of <about 15μm; (v) a sphericity Q3 [S=0.8] of equal or more than about 22%; and(vi) a Scott density of >0.2 g/cm3.
 80. The process according to claim74, wherein the carbonaceous binder precursor material to be used instep (a) is selected from the group consisting of polymers such as alignin-based polymer, a polystyrene or derivative thereof,styrene-butadiene, melted phenol resin, polyvinylalcohol, polyfurfurylalcohol, furfural, polyurethane, polystyrene-acrylate, polyacrylate,polymethylmethacrylate, polymethacrylonitrile, polyoxymethylene,poly(methyl atropate), polyisobutene, polyethyleneoxide,polypropyleneoxide, polyethylene, polypropylene, polymethylacrylate,polybutadiene, polyisoprene, polyacrylonitrile, polyaniline, tannicacid, starch, gum arabic, maltodextrin, formaldehyde phenol resins,formaldehyde tetrahydrofuran resins, nitrile butyl rubber, sucrose,glucose, or other sugars, polyethyl ether ketone, polyphenylene sulfide,polyvinyl chloride, carboxymethylcellulose, methyl cellulose, gelatins,polyvinyl pyrrolidone, polylactic acid, latexes thereof, a hydrocarbongas such as methane, ethane, ethylene, propane, propene, acetylene,butane, benzene, toluene, xylene, or an alcohol such as ethanol,propanol, isopropanol, mixed with an inert carrier gas, and combinationsthereof.
 81. The process according to claim 74, wherein the attachmentof the carbonaceous binder precursor material to the surface of thecarbonaceous particles is achieved by a method selected from the groupconsisting of: i) mixing to form a dispersion, optionally in thepresence of a solvent and subsequent drying; ii) melting thecarbonaceous binder precursor onto the primary particles; (iii)pyrolysis; (iv) pitch-coating; and (v) evaporation.
 82. The processaccording to claim 74, wherein the agglomeration of step (c) is achievedby spray-drying a dispersion comprising the primary carbonaceousparticles and the carbonaceous binder precursor material.
 83. Theprocess according to claim 74, wherein the drying of step (b) and theagglomeration of step (c) is achieved by at least one of: spray-drying adispersion comprising the primary carbonaceous particles and thecarbonaceous binder precursor material obtained from step (a) in a spraydryer; vacuum-drying a dispersion comprising the primary carbonaceousparticles and the carbonaceous binder precursor material obtained fromstep (a) in a heatable vacuum reactor; freeze-drying a dispersioncomprising the primary carbonaceous particles and the carbonaceousbinder precursor material obtained from step (a) in a stirred freezedryer; flash-drying a dispersion comprising the primary carbonaceousparticles and the carbonaceous binder precursor material obtained fromstep (a) in a flash dryer; drying a fluidized dispersion comprising theprimary carbonaceous particles and the carbonaceous binder precursormaterial obtained from step (a) in a fluidized bed dryer, optionally incombination with a spray system; disc drying a dispersion comprising theprimary carbonaceous particles and the carbonaceous binder precursormaterial obtained from step (a) in a disc dryer; and paddle drying adispersion comprising the primary carbonaceous particles and thecarbonaceous binder precursor material obtained from step (a) in apaddle dryer.
 84. The process according to claim 74 further comprising:(d) carbonizing said carbonaceous binder precursor material attached tothe surface of the agglomerated particles from step (c) by a thermaldecomposition under vacuum or an inert atmosphereat temperatures rangingfrom 400° C. to 3500° C.
 85. The process according to claim 84, whereinprior to the carbonizing of step (d), the coated agglomeratedcarbonaceous particles are subjected to a pre-treatment performed undervacuum, air, nitrogen, argon or CO₂ atmosphere at temperatures of below1000° C.
 86. The process according to claim 84, wherein the particlesobtained from step (d) are subjected to an additional heat treatment ina gas atmosphere selected from one of: nitrogen, argon, mixtures ofnitrogen with hydrocarbons like acetylene, propane or methane, or withoxidative gases such as air, steam, or CO₂ to adjust the morphology andsurface chemistry of the carbonaceous composite particles.
 87. Theprocess according to claim 84, wherein the particles obtained from step(d) are subjected to an additional heat treatment performed bycontacting the particles with an oxidant either in a gaseous/solid phaseprocess with air, carbon dioxide, water vapor, oxygen, ozone, or anycombination thereof, or, alternatively, in a liquid/solid phase processwith aqueous hydrogen peroxide or other oxidants present in said liquidphase.
 88. A process for preparing carbonaceous composite particles,comprising: (a) attaching a carbonaceous binder precursor material tothe surface of carbonaceous particles thereby forming a coating of thecarbonaceous particles by the carbonaceous binder precursor material;and (b) during or after step (a), causing agglomeration of the coatedprimary carbonaceous particles.
 89. The process according to claim 88,wherein the particle size distribution of said carbonaceous particlesemployed in step (a) is characterized by at least one of: i) a D90 of<35 μm, ii) a D50 of <about 20 μm, iii) a D90 of <25 μm, and iv) a D50of <about 15 μm; (v) a sphericity Q3 [S=0.8] of equal or more than about22%; and (vi) a Scott density of >0.2 g/cm3.
 90. The process accordingto claim 88, wherein the agglomeration of step (b) is achieved byspray-drying a dispersion comprising the primary carbonaceous particlesand the carbonaceous binder precursor material.
 91. The processaccording to claim 88 further comprising: (c) carbonizing saidcarbonaceous binder precursor material attached to the surface of theagglomerated particles from step (b) by a thermal decomposition undervacuum or an inert atmosphere at temperatures ranging from 400° C. to3500° C.
 92. The process according to claim 91, wherein prior to thecarbonizing of step (c), the coated agglomerated carbonaceous particlesare subjected to a pre-treatment performed under vacuum, air, nitrogen,argon or CO₂ atmosphere at temperatures of below 1000° C.
 93. Theprocess according to claim 91, wherein the particles obtained from step(c) are subjected to an additional heat treatment by one of: i) heatingthe particles in a gas atmosphere selected from one of: nitrogen, argon,mixtures of nitrogen with hydrocarbons like acetylene, propane ormethane, or with oxidative gases such as air, steam, or CO₂ to adjustthe morphology and surface chemistry of the carbonaceous compositeparticles; ii) heating the particles in the presence of an oxidant in agaseous/solid phase process with air, carbon dioxide, water vapor,oxygen, ozone, or any combination thereof; and iii) heating theparticles in the presence of an oxidant in a liquid/solid phase processwith aqueous hydrogen peroxide or other oxidants present in said liquidphase.